Hustedt’s study of the diatom species Tetracyclus ellipticus: why history is not just a chronicle of events

Abstract

In 1914 Hustedt presented a monographic revision of the genus Tetracyclus Ralfs. His paper was a detailed account of his investigations made for the illustrations of the genus in Schmidt’s Atlas. Hustedt made a particularly detailed study of the species T. ellipticus and outlined his ideas of the interrelationships between the subspecific taxa he understood to be “organised” around the nominate type. The monograph was unusual (and unique) in that Hustedt included a schematic diagram which represented his views on the “interrelationships” of symmetry characters observed between the various subspecific taxa he recognised. I show that Hustedt’s diagram can be related to a particular understanding of both species definitions and taxonomic practice and that others who have followed Hustedt (by implication) move further away from, rather than closer to, the data they are attempting to explain in a systematic framework.